Question: What problem would you most like to solve in the scientific world?

Laurence Perreault Levasseur answered on 16 Jun 2014:

In an ideal world where anything is possible and I can solve anything I’d like to figure out a way to make cold nuclear fusion, because that would provide a clean, green, almost unlimited source of energy to humanity, and it could be used to power interstellar travels!! However it’s unlikely this will become possible in my lifetime.

The current world being what it is, and what I can do being what I can do, in my career I’d like to understand how the classical Universe we observe around us emerges from the probabilistic laws of quantum mechanics.

Here’s what it means: At really really small distances, like at the scales of atoms and even smaller distances, we have a theory of physics that is called quantum mechanics. It’s a theory that works really well, and is extremely well tested. Because of it, we have been able to make computers, cellphones, internet, anything that has transistors, electron microscopes, etc… It has literally changed the world.

The thing is that this theory is VERY weird. It says that particles behave in a probabilistic way, sometimes a bit like waves propagates on the surface of the water when you drop a rock on a pond, and sometimes really like a little ball that can move around. This is very weird, the idea that electrons can be like a wave. For example, if I ask ‘where is the wave?’ there is no definite answer, the wave is at a lot of places at the same time. The same is true for electrons, and all fundamental particles. It’s like asking ‘where am I?’ and not being able to answer because I’m a bit spread out between Paris and California and Cambridge. That makes no sense to use this theory to say things at a more human scales!

But, if inflation is correct, all that we observe today in the Universe around us came from those really tiny small scales where quantum mechanics rules, and were inflated at the scales of humans and galaxies. So a fundamental problem is to understand how this transition happens between this ‘weird behaviour’ to ‘more normal behaviour’. That’s the problem I’d like to solve.